The contribution of the pressure gradient (acoustic component) and gravity (gravity component) to the wave variations of parameters of high-latitude thermosphere was investigated with the use of measurements from the low-orbit satellite Dynamic Explorer 2. It was found that the wave disturbances which are systematically dominated in the polar region at altitudes of 250—400 km have acoustic and gravitational components with close magnitude and spectral characteristics. The obtained ratio of acoustic and gravitational parts reveals a peculiar energy balance of these waves.